Sensors based on sorptive-mechanical transducers for detection of physiological parameters according to the intramolecular compensation method

快速检测人体内低浓度的生理相关物质仍然是生物医学工程的主要挑战。这些参数通常存在于溶液中，包括凝血酶、葡萄糖、pH值和各种离子浓度。然而，合适的微传感器的开发，没有它的即时诊断几乎是不可想象的，总是发现自己在一方面传感器小型化和传感器的三个核心特性之间的冲突领域：刺激响应性水凝胶，其根据溶液中存在的测量物质占据一定体积，可用作微传感器中的吸附机械换能器。然后通过机电换能器（例如压阻式压力传感器）将测量的变量相关膨胀压力转换成电输出信号。然而，由于体积相变，这些小型化的基于水凝胶的传感器具有长的测量时间。近年来，分子内补偿的测量方法被提出来弥补水凝胶传感器的这些缺点。测量方法的目的是抑制传感器中水凝胶的溶胀。通过保持在溶胀平衡，冗长的溶胀过程被抵消，传感器的性能得到大幅改善。因此，测量时间可以减少高达70%。此外，补偿方法允许扩展测量范围并抵消粘弹性蠕变。为了为更广泛的应用铺平道路，用于制造补偿传感器的快速可靠的制造工艺特别令人感兴趣。水凝胶传感器也应该变得生物相容。Solzbacher教授（犹他州大学）的研究小组在水凝胶传感器的开发方面处于领先地位，该传感器使用聚酰亚胺基悬臂作为膨胀压力传感器，因此具有生物相容性。该研究项目的目的是将分子内补偿的测量方法与Solzbacher小组的相对简单且生物相容的水凝胶传感器相结合。同时，将开发具有生理相关敏感性（例如葡萄糖）的进一步补偿性水凝胶。从长远来看，这将为可靠的小型化生物传感器铺平道路，这些传感器可以集成到导管尖端中，例如，直接测量患者血液中的溶解物质（例如麻醉气体），并且几乎是真实的时间。

The rapid detection of low concentrations of physiologically relevant species in the human body still poses major challenges in biomedical engineering. These parameters, which are usually present in solution, include thrombin, glucose, the pH value and various ion concentrations. However, the development of suitable microsensors, without which point-of-care diagnosis is hardly conceivable, always finds itself in the field of conflict between sensor miniaturization on the one hand and the three core characteristics of a sensor: sensitivity, selectivity and stability on the other.Stimulus-responsive hydrogels, which occupy a certain volume depending on a measuring species present in solution, can be used as sorptive-mechanical transducers in microsensors. The measured variable-dependent swelling pressure is then converted into an electrical output signal by a mechanoelectric transducer, e.g. a piezoresistive pressure sensor. However, these miniaturized hydrogel-based sensors have long measuring times due to the volume phase transitions. Recently, the measuring method of intramolecular compensation was presented to counteract these disadvantages of hydrogel-based sensors. The aim of the measuring method is to suppress the swelling of the hydrogel in the sensor. By staying in the swelling equilibrium, tedious swelling processes are counteracted and the sensor properties are drastically improved. Thus a reduction of the measuring time by up to 70% could be achieved. Furthermore, the compensation method allows to extend the measuring range and to counteract viscoelastic creep. To pave the way for a wider range of applications, a fast and reliable manufacturing process for the fabrication of compensated sensors is of special interest. The hydrogel sensor should also become biocompatible. The research group of Prof. Solzbacher (University of Utah) is leading in the development of hydrogel-based sensors, which use a polyimide-based cantilever as swelling pressure transducer and thus offer biocompatibility.The aim of the research project is to combine the measuring method of intramolecular compensation with the comparatively simpler and biocompatible hydrogel sensors of the Solzbacher group. At the same time, further compensatory hydrogels with physiologically relevant sensitivities (e.g. glucose) are to be developed. In the long term, this should pave the way for reliable, miniaturized biosensors that can be integrated into catheter tips, for example, to measure dissolved substances (e.g. anesthetic gases) directly in a patient's blood and in almost real time.